The present invention is directed to electronic circuitry and, more particularly, to voltage level shifters.
A semiconductor device, such as an integrated circuit (IC) or the like, may operate using multiple voltage levels. For example, an IC may have multiple internal modules having different functions and requiring different operating voltages. A voltage level shifter is a circuit that is used to convert signal levels to higher or lower voltages.
When an IC operating on a lower supply voltage communicates with an IC operating on a higher supply voltage, the transistors in the level shifter of the lower supply voltage IC can be subject to over-voltage stress. That is, voltage swings across the terminals of the transistors may exceed permissible levels, negatively impacting the reliability of the circuit and potentially causing damage to the IC.
It is therefore desirable to provide a level shifter which has built-in protection for withstanding over-voltage stresses while still maintaining high speed operation with low power consumption.